<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .three_block {
            display: flex;
            flex-direction: row;
            justify-content: space-between;
            height: 900px;
        }
        .left {
            width: 33%;
            background-color: white;
        }
       .center {
            width: 33%;
            /* height: 200px; */
            background-color: whitesmoke;
        }
       .right {
        width: 33%;
        background-color: white;
       }
    </style>
</head>
<body>
    <div class="three_block">
        <div class="left"></div>
        <div class="center"></div>
        <div class="right"></div>
    </div>
</body>
</html>